remote_storage: enable Azure connection pooling by default

libs/remote_storage/src/config.rs

@@ -115,13 +115,15 @@ fn default_max_keys_per_list_response() -> Option<i32> {
 }
 
 fn default_azure_conn_pool_size() -> usize {
-    // Conservative default: no connection pooling.  At time of writing this is the Azure
-    // SDK's default as well, due to historic reports of hard-to-reproduce issues
+    // By default, the Azure SDK does no connection pooling, due to historic reports of hard-to-reproduce issues
     // (https://github.com/hyperium/hyper/issues/2312)
     //
     // However, using connection pooling is important to avoid exhausting client ports when
     // doing huge numbers of requests (https://github.com/neondatabase/cloud/issues/20971)
-    0
+    //
+    // We therefore enable a modest pool size by default: this may be configured to zero if
+    // issues like the alleged upstream hyper issue appear.
+    8
 }
 
 impl Debug for S3Config {